1. Field of the Invention
The present invention relates to an optical scanning apparatus for use in an image forming apparatus, such as a copying machine, a facsimile machine, and a laser beam printer. More particularly, the present invention relates to an optical scanning apparatus for performing deflection scanning of a laser beam using a deflection mirror (microelectromechanical system (MEMS) mirror) manufactured using MEMS technology.
2. Description of the Related Art
In recent years, there has been a demand for further reduction in the sizes of electrophotographic image forming apparatuses, such as copying machines and laser beam printers for use in offices, especially, of a compact desktop image forming apparatus.
Japanese Patent Application Laid-Open No. 7-299928 discusses a small laser beam printer that employs an S-shaped path as a recording medium conveying path. With such a configuration, all of sheet-feeding, image-forming, fixing, and sheet-discharging operations can be performed within the installation area of the body of the printer.
On the other hand, various optical scanning apparatuses each including a light deflection device, which employs an MEMS mirror, have been proposed. The optical scanning apparatuses each including a light deflection device employing an MEMS mirror, have a feature that the light deflection device itself can considerably be reduced in size, as compared with an optical scanning apparatus using a rotatable polygonal mirror.
In addition, the optical scanning apparatuses using a light deflection device employing an MEMS mirror also have features that power consumption is low and that a silicon single-crystal MEMS mirror manufactured by a semiconductor process is theoretically metal-fatigueless and excels in durability.
Japanese Patent Application Laid-Open No. 9-80348 discusses a technology of performing optical scanning utilizing a reflection mirror that performs sine vibrations in a light deflection device using an MEMS mirror. Japanese Patent Application Laid-Open No. 2005-208578 discusses a technology of simultaneously exciting two or more natural vibration modes in a torsional vibration direction to perform optical scanning other than the optical scanning by sine vibrations.
To further reduce the installation area of an image forming apparatus, it is necessary not only to devise the conveying path but also to further miniaturize various components provided in the image forming apparatus.
More specifically, the optical scanning apparatus should be installed so as not to interfere with a locus of a process cartridge during the attachment/detachment of the process cartridge by a user, while the optical scanning apparatus is disposed close to the process cartridge in order to irradiate laser light onto a photosensitive member of the process cartridge.
Accordingly, it is requested to further reduce the size of the optical scanning apparatus itself.